As a plasma display panel (hereinafter referred to as a PDP), a direct-current type (DC type) PDP and an alternate-current type (AC type) PDP are known. These PDPs are further classified into a so-called mono-color type PDP using the emission of light by a discharge gas and a color type PDP in which a fluorescent substance is caused to emit visible light by ultraviolet rays generated by discharge. Although the following problems arise in both the color and the nono-color type PDPs, they are significant particularly in the color type PDP, so the color PDP will be described mainly below.
Although various methods of arranging PDPs are known, an air-tight vessel containing a discharge gas, which is manufactured by sealing the peripheral portions of front glass and rear plates opposing each other with sealing glass in order to decrease the thickness of the structure, is frequently adopted. Commonly, inexpensive soda-lime glass is used for both the front and rear plates.
In a color PDP having a large number of fine display cells. diaphragms are formed between the front and rear plates in order to prevent an erroneous discharge or a blur of colors between adjacent cells or to keep the difference between pressures inside and outside the panel, or as spacers for defining the distances between discharge electrodes. A space surrounded by the diaphragms and the front and the rear plates functions as one display cell. A fluorescent substance is deposited on the inner surface of each display cell to emit visible light of each individual color upon irradiation with ultraviolet rays generated by discharge. In the formation of the diaphragms, a thick-film formation technique that prints and calcines a dielectric paste consisting of, e.g., glass on the front and rear plates is used. In addition, methods using a porous metal plate have been proposed by the present inventors in Japanese Patent Application Laid-Open gazette Nos. 3-152830, 3-205738 and 4-19942. The present invention relates to a color PDP using this porous metal plate.
In the color PDP having a large number of fine display cells capable of displaying images, a matrix cell arrangement in which cells and electrodes can be formed easily is generally adopted. It is convenient to form a number of cells at the intersections of linear row- and column-discharge electrodes formed in a matrix manner. Each group of the row- and column-electrodes is a first or second electrode group, and a large number of cells can be selected independently of one another in these two electrode groups. Therefore, the types of first and second electrode groups are not particularly limited as long as a number of cells can be selected.
In the DC type PDP, linear cathodes are formed on a front glass plate or a rear plate, and linear anodes are formed on a substrate opposing the cathodes, such that both the cathodes and the anodes are exposed to a discharge gas and cross each other with diaphragms between them. Alternatively, the cathodes and the anodes can be formed on the same substrate to cross each other via a dielectric. An arrangement using an auxiliary discharge electrode in addition to the first and second electrode groups is also known.
The AC type PDP is similar to the DC type PDP except that discharge electrodes are covered with a dielectric, so two linear electrode groups can also be formed in the AC type PDP. Write electrodes can be formed on the same substrate as the discharge electrodes via an insulating layer. In some DC type PDPs, one of a pair of electrode groups is formed to cross the other via an insulating layer, making the use of write electrodes unnecessary. There is another known arrangement in which the electrodes of one of a pair of discharge electrode groups covered with a dielectric are connected together in units of cells, and electrodes for selection, so-called write electrodes are used as exposed electrodes.
A fluorescent substance is formed on a substrate opposing a substrate on which the cathodes or the discharge electrodes are formed. This is essential to prevent deterioration in the fluorescent substance due to positive ions generated by discharge.
In the DC and the AC type PDPs, colored glass layers are sometimes formed on the front and rear plates in order to shield light and improve contrast. External extracting terminals are also required.
In these color PDPs, many of constituting elements such as circuits arc formed on the front and rear plates. Therefore, the color PDP is assembled by setting three primary components, i.e., the front glass plate, the rear plate, and the diaphragm plate made of a porous metal plate to their respective predetermined positions. That is, the thickness of a display portion of the color PDP is the sum total of the thicknesses of the front and rear plates on which the individual constituting elements are formed and the thickness of the diaphragm plate.
When glass is used for the front and rear plates, a thickness meeting the dimensions of the glass plate required for panel formation is necessary for convenience in operation. As an example, thicknesses of 1 mm, 2 mm, and about 5 mm are required for diagonal dimensions of the display portions of 6 to 10 inches, 10 to 20 inches, and 40 inches or more, respectively. This thickness of the rear plate cannot be neglected in a flat display panel required to be light in weight and thin.
In addition, the arrangement constituted by the front and rear plates and the diaphragm plate requires two-time positioning, i.e., the number of times of positioning is larger than that in a PDP constituted by the front and rear plates alone. That is, the number of times of positioning is increased as the number of parts increases, and this disadvantage is significant particularly in a color PDP manufactured through cumbersome steps and having fine cells.
At present, as described above, many problems are left unsolved in the conventional PDPs.
The present invention has been made in consideration of the above conventional situations, and has as its object to provide a PDP which is light in weight and thin and can be assembled easily.